As a crucial component of flexible electronic devices, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-based hydrogels for strain sensors have garnered extensive attention for their potential in the field of wearable sensors due to their inherent conductivity and flexibility. However, challenges such as poor mechanical strength, limited sensitivity, and poor durability have hindered the widespread application of PEDOT:PSS hydrogels in high-performance strain sensors. In this study, we develop a novel PEDOT:PSS-P(HEMA-co-AA) hydrogel that addresses common limitations in hydrogel applications, demonstrating remarkable stretchability, low hysteresis, and reliable conductivity. The hydrogel is synthesized using a semi-interpenetrating polymer network (SIPN) strategy, combining the linear conducting polymer PEDOT:PSS with a chemically cross-linked network based on 2-hydroxyethyl methacrylate (HEMA) and acrylic acid (AA). This hybrid structure notably contributes to the hydrogel's mechanical properties, achieving a stretchability of 195 %, while maintaining a rapid response time of 0.20 seconds and exceptional cyclic stability over 1000 cycles under 100 % strain. Moreover, the hydrogel demonstrates promising strain-sensing capabilities, positioning it as a strong candidate for future applications in wearable electronics and flexible sensors. The adoption of the SIPN strategy, along with the synergistic combination of PEDOT:PSS and P(HEMA-co-AA), paves a new pathway for enhancing the mechanical performance and sensing properties of hydrogels in strain-sensing technologies.
Wang Jianying,Ma Xiaofei,Wei Lai,Zhu Xiang,Zhu Yuhua,Wang Gang,Mei Tao,Li Jinhua,Wang Xianbao
A novel kind of p(HEMA-co-AA) fluorescent hydrogels with high strength are first generated through one-step photopolymerization of 2-hydroxyethyl methacrylate (HEMA), acrylic acid (AA), and HEMA-modified carbon dots (HMCDs). Herein, HMCDs are used as new nontoxic fluorescent crosslinking centers. The novel HMCDs-based fluorescent hydrogels not only display stable photoluminescence, but have high mechanical strength. The fluorescent properties of the HMCDs-based hydrogel films are similar as that of CDs solution and stable for a prolonged duration. Besides, the fluorescent intensity of HMCDs-based hydrogels can be changed by controlling the HMCD content. The tensile strength of the fluorescent hydrogels with 1 wt% HMCD content can reach up to ~ 12 MPa, higher than that of the conventional hydrogels. More importantly, the mechanical properties can be adjusted by changing the water content and HMCD content. The enhanced mechanical strength is probably attributed to the relatively ordered hierarchical microstructure.
2-Hydroxyethyl methacrylate (HEMA) improved colloids of silica/carbon dots (SiO2/HMCDs) were used by means of new translucent, nontoxic cross-linking centers comprising two non-toxic components, silica colloids and carbon dots. The direct photopolymerization of a mixture
of acrylic acid (AA), HEMA, and SiO2/HMCDs afforded ultrahigh strength and mechanically robust hydrogel. The fabricated fluorescent SiO2/HMCDs-based hydrogels demonstrated stable photoluminescence owing to their outstanding mechanical flexibility. Fluorescent hydrogels
exhibited tensile strength of up to ∼ 13.2 MPa by processing with 1 wt% SiO2/HMCDs content. More importantly, the mechanical properties (stress or strain) could be changed by controlling the content of SiO2/HMCDs and H2O. Relative hierarchical structure
attributed to high mechanical strength.